3
Q:

Which of the following group is NOT Dobereiner Triads?

 

A) Li, Na, K B) N, P Au
C) Cl, Br, I D) Ca, Sr, Ba

Answer:   B) N, P Au



Explanation:
Subject: Chemistry
Exam Prep: Bank Exams
Q:

Chloroform used as anaesthetic should be preserved in the dark in tightly stoppered bottles because otherwise

A) it becomes coloured B) it gets evaporated in air
C) it gets oxidised to phosgene D) it gets decomposed to chloropicrin
 
Answer & Explanation Answer: C) it gets oxidised to phosgene

Explanation:

Chloroform, CHCl3 is easily oxidised to the highly poisonous gas known as phosgene or carbonyl chloride COCl2. Hence if it is used as anaesthetic it should be kept free from sunlight and air.

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Filed Under: Chemistry
Exam Prep: AIEEE

9 4348
Q:

Dust particles in the air of large industrial cities are removed by 

A) Sedimentation B) Electrophoresis
C) Tyndall effect D) Brownian movement
 
Answer & Explanation Answer: B) Electrophoresis

Explanation:

Dust particles such as coal dust(smoke) are fine particle of a solid (carbon in the case of smoke) dispersed in air. They are colloidal systems and the particles are charged either positive or negative. In an applied electrical field, they are attracted towards the opposite electrodes. Movement of the particles towards the electrodes is known as 'electrophoresis'. Hence electrophoresis is applied to remove smoke within the chimeny itself without allowing it to escape into the air and cause nuisance.

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3 2942
Q:

Stainless steel contains steel and 

A) manganese B) vanadium
C) nickel D) chromium
 
Answer & Explanation Answer: D) chromium

Explanation:

Stainless steel contains 18% chromium and 82% steel

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4 2531
Q:

The purest form of iron is 

A) wrought iron B) steel
C) pig iron D) nickel steel
 
Answer & Explanation Answer: A) wrought iron

Explanation:

Wrought Iron is the purest form of iron. It contains 0.12 to 0.25% carbon and so it is the purest form of iron.

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Exam Prep: GATE , CAT , Bank Exams , AIEEE
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822 93830
Q:

In the making of jewels, gold is usually mixed with 

A) zinc B) tin
C) copper D) aluminium
 
Answer & Explanation Answer: C) copper

Explanation:

In making jewels, gold is usually mixed with copper to make it little hard.

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2 2958
Q:

In photography, the compound of nitrogen used is 

A) Potassium nitrate B) Silver nitrate
C) Ammonium carbonate D) Ammonium bicarbonate
 
Answer & Explanation Answer: B) Silver nitrate

Explanation:

Silver nitrate is the basic substance from which silver bromide is obtained. The photographic films are impregnated with the light sensitive AgBr.

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12 6382
Q:

Which of the following acts both as oxidising and reducing agent?

A) nitric acid B) ammonia
C) nitrous acid D) nitrogen peroxide
 
Answer & Explanation Answer: C) nitrous acid

Explanation:

Nitrous acid act as an oxidising agent because it oxidises potassium iodide to iodine. It is also a reducing agent because it decolourises acidified potassium permanganate solution.

Nitric acid acts only as an oxidising agent

Ammonia acts only as a reducing agent

Nitrogen peroxide acts only as an oxidising agent.

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12 7976
Q:

Leakage in LP gas cylinders is easily detected by adding

A) mercaptans B) propylene
C) carbon disulphide D) phosgene
 
Answer & Explanation Answer: A) mercaptans

Explanation:

mercaptans (or thioalcohols) have a foul odour

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7 4403